25 ideas
| 7914 | To try to be wise all on one's own is folly [Rochefoucauld] |
| Full Idea: To try to be wise all on one's own is sheer folly. | |
| From: La Rochefoucauld (Maxims [1663], 231) | |
| A reaction: I agree strongly with this. There are counter-examples, of whom Spinoza may be the greatest, and Nietzsche thought that philosophy was essentially a solitary business, but most of us are not Spinoza or Nietzsche. |
| 13838 | A decent modern definition should always imply a semantics [Hacking] |
| Full Idea: Today we expect that anything worth calling a definition should imply a semantics. | |
| From: Ian Hacking (What is Logic? [1979], §10) | |
| A reaction: He compares this with Gentzen 1935, who was attempting purely syntactic definitions of the logical connectives. |
| 13833 | 'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking] |
| Full Idea: 'Dilution' (or 'Thinning') provides an essential contrast between deductive and inductive reasoning; for the introduction of new premises may spoil an inductive inference. | |
| From: Ian Hacking (What is Logic? [1979], §06.2) | |
| A reaction: That is, inductive logic (if there is such a thing) is clearly non-monotonic, whereas classical inductive logic is monotonic. |
| 13834 | Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking] |
| Full Idea: If A |- B and B |- C, then A |- C. This generalises to: If Γ|-A,Θ and Γ,A |- Θ, then Γ |- Θ. Gentzen called this 'cut'. It is the transitivity of a deduction. | |
| From: Ian Hacking (What is Logic? [1979], §06.3) | |
| A reaction: I read the generalisation as 'If A can be either a premise or a conclusion, you can bypass it'. The first version is just transitivity (which by-passes the middle step). |
| 13835 | Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking] |
| Full Idea: Only the cut rule can have a conclusion that is less complex than its premises. Hence when cut is not used, a derivation is quite literally constructive, building up from components. Any theorem obtained by cut can be obtained without it. | |
| From: Ian Hacking (What is Logic? [1979], §08) |
| 13845 | The various logics are abstractions made from terms like 'if...then' in English [Hacking] |
| Full Idea: I don't believe English is by nature classical or intuitionistic etc. These are abstractions made by logicians. Logicians attend to numerous different objects that might be served by 'If...then', like material conditional, strict or relevant implication. | |
| From: Ian Hacking (What is Logic? [1979], §15) | |
| A reaction: The idea that they are 'abstractions' is close to my heart. Abstractions from what? Surely 'if...then' has a standard character when employed in normal conversation? |
| 13840 | First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking] |
| Full Idea: First-order logic is the strongest complete compact theory with a Löwenheim-Skolem theorem. | |
| From: Ian Hacking (What is Logic? [1979], §13) |
| 13844 | A limitation of first-order logic is that it cannot handle branching quantifiers [Hacking] |
| Full Idea: Henkin proved that there is no first-order treatment of branching quantifiers, which do not seem to involve any idea that is fundamentally different from ordinary quantification. | |
| From: Ian Hacking (What is Logic? [1979], §13) | |
| A reaction: See Hacking for an example of branching quantifiers. Hacking is impressed by this as a real limitation of the first-order logic which he generally favours. |
| 13842 | Second-order completeness seems to need intensional entities and possible worlds [Hacking] |
| Full Idea: Second-order logic has no chance of a completeness theorem unless one ventures into intensional entities and possible worlds. | |
| From: Ian Hacking (What is Logic? [1979], §13) |
| 13837 | With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking] |
| Full Idea: My doctrine is that the peculiarity of the logical constants resides precisely in that given a certain pure notion of truth and consequence, all the desirable semantic properties of the constants are determined by their syntactic properties. | |
| From: Ian Hacking (What is Logic? [1979], §09) | |
| A reaction: He opposes this to Peacocke 1976, who claims that the logical connectives are essentially semantic in character, concerned with the preservation of truth. |
| 13839 | Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking] |
| Full Idea: For some purposes the variables of first-order logic can be regarded as prepositions and place-holders that could in principle be dispensed with, say by a system of arrows indicating what places fall in the scope of which quantifier. | |
| From: Ian Hacking (What is Logic? [1979], §11) | |
| A reaction: I tend to think of variables as either pronouns, or as definite descriptions, or as temporary names, but not as prepositions. Must address this new idea... |
| 13843 | If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking] |
| Full Idea: A Löwenheim-Skolem theorem holds for anything which, on my delineation, is a logic. | |
| From: Ian Hacking (What is Logic? [1979], §13) | |
| A reaction: I take this to be an unusually conservative view. Shapiro is the chap who can give you an alternative view of these things, or Boolos. |
| 7118 | La Rochefoucauld's idea of disguised self-love implies an unconscious mind [Rochefoucauld, by Sartre] |
| Full Idea: La Rochefoucauld is one of the first to have made use of the unconscious without naming it: for him, amour-propre conceals itself in the most diverse disguises. | |
| From: report of La Rochefoucauld (Maxims [1663]) by Jean-Paul Sartre - Transcendence of the Ego I (C) | |
| A reaction: It seems odd that no one before that ever thought that someone might have hidden motives of which even they themselves were unaware. How about Iago, or Macbeth, or Hamlet? It is a profound change in our view of human nature. |
| 2848 | Two people might agree in their emotional moral attitude while disagreeing in their judgement [Brink] |
| Full Idea: Critics of emotivism claim that moral agreement need not track agreement in attitude; moralists with the same attitude can disagree in their views, and they can hold the same view while disagreeing in attitude. | |
| From: David O. Brink (Emotivism [1995], p.224) | |
| A reaction: Thus two racists can disagree about how racists should behave. Sounds like a good criticism. |
| 2851 | Emotivists find it hard to analyse assertions of moral principles, rather than actual judgements [Brink] |
| Full Idea: It is hard for the emotivist to give an analysis of the occurrence of moral ideas in unasserted contexts, such as "IF he did wrong, then he should be punished". | |
| From: David O. Brink (Emotivism [1995], p.224) | |
| A reaction: This is the 'Frege-Geach Problem'. |
| 2853 | Emotivists claim to explain moral motivation by basing morality on non-cognitive attitudes [Brink] |
| Full Idea: By stressing the intimate connection between moral judgements and the agent's non-cognitive attitudes, emotivists claim to capture the motivational properties of moral judgement. | |
| From: David O. Brink (Emotivism [1995], p.223) | |
| A reaction: The same claim is made by contractarians, who start from our universal self-interest. Emotivists also nicely capture the motivation properties of immoral judgements. |
| 2852 | Emotivists tend to favour a redundancy theory of truth, making moral judgement meaningless [Brink] |
| Full Idea: If you want to recognise the truth of some moral judgements, perhaps to make room for the possibility of moral mistakes, then one may not be satisfied with the emotivists' tendency to appeal to the redundancy theory of truth. | |
| From: David O. Brink (Emotivism [1995], p.224) | |
| A reaction: Probably thinking of Simon Blackburn. People who adopt a redundancy view of truth for semantics are left floundering when discussing what is true in the rest of philosophy. |
| 2849 | Emotivism implies relativism about moral meanings, but critics say disagreements are about moral reference [Brink] |
| Full Idea: Emotivism suggests that different feelings lead to different individual meanings for moral terms, but critics say that meanings are the same, and disagreement is about the extension (range of reference) of the terms. | |
| From: David O. Brink (Emotivism [1995], p.224) | |
| A reaction: It's hard to see how 'ought to p' could have quite different meanings for an emotivist and (say) a theistic moralist. 'Ought' is an obvious and simple word. Good criticism. |
| 2850 | How can emotivists explain someone who recognises morality but is indifferent to it? [Brink] |
| Full Idea: It is not clear how the emotivist can accommodate the amoralist - one who recognises moral requirements but is indifferent to them. | |
| From: David O. Brink (Emotivism [1995], p.224) | |
| A reaction: Nietzsche recognised current morals, but was indifferent to them. It is hard to imagine, though, an amoralist who lacked all the feelings which imply morality. |
| 7912 | Judging by effects, love looks more like hatred than friendship [Rochefoucauld] |
| Full Idea: If love be judged by its most visible effects it looks more like hatred than friendship. | |
| From: La Rochefoucauld (Maxims [1663], 072) | |
| A reaction: Presumably he is thinking of pursuit, possession and jealousy. The remark is plausible if you add the word 'sometimes' to it, but as a universal generalisation it is ridiculous, the product of a society where they competed to exceed in cynicism. |
| 7915 | Supreme cleverness is knowledge of the real value of things [Rochefoucauld] |
| Full Idea: Supreme cleverness is knowledge of the real value of things. | |
| From: La Rochefoucauld (Maxims [1663], 244) | |
| A reaction: Good. Right at the heart of wisdom is some kind of grasp of right values. It is so complex and subtle that it seems like pure intuition, but I am sure that reason is involved. 'Intelligent' people tend to be better at it. Some justifications can be given. |
| 7917 | Realising our future misery is a kind of happiness [Rochefoucauld] |
| Full Idea: To realise how much misery we have to face is in itself a kind of happiness. | |
| From: La Rochefoucauld (Maxims [1663], 570) | |
| A reaction: Probably true. Knowing that you have got hold of the truth is a sort of happiness in any area, no matter how grim the truth. However, a happy life could easily be poisoned by brooding on the future. Should the happily married brood on future solitude? |
| 7913 | Virtue doesn't go far without the support of vanity [Rochefoucauld] |
| Full Idea: Virtue would not go far without vanity to bear it company. | |
| From: La Rochefoucauld (Maxims [1663], 200) | |
| A reaction: Rochefoucauld's cynicism gets a bit tedious, but lovers of virtue must face up to this possibility when they consider what motivates them. At the heart of Aristotle there is a missing question, of what is so good about right-functioning and virtue. |
| 7916 | True friendship is even rarer than true love [Rochefoucauld] |
| Full Idea: Rare though true love may be, true friendship is rarer still. | |
| From: La Rochefoucauld (Maxims [1663], 473) | |
| A reaction: This seems to be true. Our culture doesn't encourage friendship as a high ideal. Are women better at friendship than men? Which culture, past or present, led to the greatest flourishing of friendship? Epicurus's Garden? |
| 9299 | We are bored by people to whom we ourselves are boring [Rochefoucauld] |
| Full Idea: Almost always we are bored by people to whom we ourselves are boring. | |
| From: La Rochefoucauld (Maxims [1663], 555) | |
| A reaction: An obvious exception would be a celebrity being bored with their fans. Their very excess of interest is precisely what is boring. If two people communicate well, it is unlikely that either of them will ever be bored. |